Exhaust Gas Filter System

ABSTRACT

An exhaust gas filter system in which an asymmetrical channel, in which the diameter of an inlet being opened is larger than that of an outlet disposed and opened at a rear end surface, is formed, may include a first coating layer that is formed at an inner surface of a front portion of the channel by coating a first wash coat, and a second coating layer that is formed at an inner surface of a rear portion of the channel by coating a second wash coat, wherein inner cross section of the front portion is wider than inner cross section of the rear portion.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application Number 10-2008-0123525 filed Dec. 5, 2008, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exhaust gas filter system, and more particularly to an exhaust gas filter system for reducing back pressure of exhaust gas and improving purification efficiency of particulate matter.

2. Description of Related Art

Generally, the exhaust system of an engine exhausts exhaust gas to the rear of a vehicle and reduces exhaust noise.

Lately, a catalyst device has been used so as to purify the exhaust gas and transform harmful exhaust gas to harmless carbon dioxide and water.

Particularly, the catalyst device reduces hydrocarbons, carbon monoxide, and nitrogen oxide (NOx). Also, the catalyst device filters or burns particulate matter. Generally, a diesel particulate filter (DPF) accumulates particulate matter that is generated from a diesel engine and combusts the accumulated matter, and a plurality of channels are formed therein in a flow direction of the exhaust gas.

Further, the inlet of at least one among the channels is closed and the outlet thereof is opened, the inlet of at least another one among the channels is closed and the outlet thereof is opened, and the closed portions are alternatively disposed.

A diesel oxidation catalyst (DOC) and a catalyzed particulate filter (CPF) among catalyst devices are applied to accumulate and to eliminate particulate matter (PM).

The filter includes expensive SiC or AT materials, and an asymmetrical filter is used so as to raise accumulation efficiency for accumulating the particulate matter. However, when accumulating the particulate matter, the back pressure and the fuel consumption increase.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention are directed to provide an exhaust gas filter system having advantages of preventing back pressure from being increased, and improving regeneration efficiency.

In an aspect of the present invention, an exhaust gas filter system in which an asymmetrical channel, in which the diameter of an inlet being opened is larger than that of an outlet disposed and opened at a rear end surface, is formed, may include a first coating layer that is formed at an inner surface of a front portion of the channel by coating a first wash coat, and/or a second coating layer that is formed at an inner surface of a rear portion of the channel by coating a second wash coat, wherein inner cross section of the front portion is wider than inner cross section of the rear portion.

The thickness of the second coating layer may be equal to or smaller than that of the first coating layer.

The first coating layer may be formed in the front portion and the second coating layer is formed in the rear portion of the filter on the basis of a center line thereof, wherein the volume of the first wash coat that is used for the first coating layer is approximately twice as large as that of the second wash coat that is used for the second coating layer.

The weight (grams) of a noble metal that is contained in the first wash coat may be equal to that of the noble metal that is contained in the second wash coat, and the concentration (grams/liter) of the noble metal is varied according to the weight of the noble metal.

In another aspect of the present invention, a plurality of channels may be formed in a flow direction of exhaust gas, the inlet of at least one among the channels is opened and the outlet thereof is closed, the inlet of at least another one among the channels is closed and the outlet thereof is opened, and the closed portions of the inlets are alternatively disposed and the closed portions of the outlets are alternatively disposed.

The front portion of the filter may be soaked in a first wash coat liquid and the rear portion of the filter is soaked in a second wash coat liquid so as to respectively form the first coating layer and the second coating layer, wherein the thickness of the first coating layer is adjusted by controlling the used volume of the first wash coat.

As described above, in various aspects of the present invention, the thickness of the coating layer of the rear portion is reduced such that back pressure is lowered and regeneration efficiency is improved.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary exhaust gas filter system according to the present invention.

FIG. 2 is a schematic side view of a filter that is disposed in an exemplary exhaust gas filter system according to the present invention.

FIG. 3 is a side view showing View A of FIG. 2.

FIG. 4 is a side view showing View B of FIG. 2.

FIG. 5 is a detailed sectional view of a filter according to line V-V and line VI-VI of FIG. 2.

FIG. 6 is a table showing characteristics of wash coat that is applied to a filter.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

FIG. 1 is a schematic diagram of an exhaust gas filter system according to various embodiments of the present invention.

Referring to FIG. 1, reference number 100 denotes a diesel engine, reference number 110 denotes an exhaust pipe, and reference number 120 denotes a diesel catalytic filter (DPF). And DOC (diesel oxidation catalyst) is disposed in upstream side of the DPF 120.

The diesel catalytic filter 120 accumulates and eliminates particulate matter including soot.

In various embodiments of the present invention, a catalyzed particulate filter (CPF) can be applied instead of the diesel catalytic filter 120.

FIG. 2 is a schematic side view of a filter that is disposed in an exhaust gas filter system according to various embodiments of the present invention, FIG. 3 is a side view showing View A of FIG. 2, and FIG. 4 is a side view showing View B of FIG. 2.

Referring to FIG. 2, a filter 200 is disposed to accumulate particulate matter in the diesel catalytic filter 120, and the filter 200 is divided into a front portion 230 and a rear portion 240 on the basis of a center line 250 thereof. And, a front end surface 210 is formed in the front end of the front portion 230 and a rear end surface 220 is formed in the rear end of the rear portion 240.

Referring to FIG. 3 and FIG. 4, a plurality of channels 310 through which the exhaust gas passes are formed in a direction from the front end surface 210 to the rear end surface 220 of the filter 200.

The channels 310 that are formed in the front end surface 210 are alternatively closed by a first plug 300 and the channels 310 that are formed in the rear end surface 220 are alternatively closed by a second plug 320.

More specifically, the cross-section of the channel 310 of which the inlet thereof is opened and the outlet thereof is closed by the second plug 320 becomes narrower in a length direction of the filter 200.

In contrast, the inlet thereof is closed by the first plug 300 and the outlet thereof is opened.

As described above, the filter 200 has an asymmetrical structure in which the inlet is larger than the outlet to effectively improve the accumulation amount of the PM and to increase a valid volume thereof such that the filter volume and the production cost can be reduced.

FIG. 5 is a detailed sectional view of a filter according to line V-V and line IV-IV of FIG. 2.

Referring to FIG. 5, a first coating layer 500 that is formed in the front portion 230 of the filter 200 is formed at an inner surface of the channel 310, and a second coating layer 505 that is formed in the rear portion 240 of the filter 200 is formed at an inner surface of the channel 310.

The thickness d1 of the first coating layer 500 is equal to or greater than the thickness d2 of the second coating layer 505 such that an increase in back pressure is prevented toward the rear of the filter 200.

That is, although ash and soot are accumulated in the rear portion, the back pressure that is formed in the second coating layer is relatively low.

FIG. 6 is a table showing characteristics of wash coat that is applied to a filter.

Referring to FIG. 6, the first wash coat is used to form the first coating layer 500 that is formed in the front portion 230 of the filter 200, and the second wash coat is used to form the second coating layer 505 in the rear portion 240.

In various embodiments of the present invention, the used volume of the first wash coat is equal to or larger than that of the second wash coat.

As described above, the used volume of the first wash coat that is used for the wider area and the thickness d1 of the first coating layer 500 are equal to or greater than the used volume of the second wash coat and the thickness d2 of the second coating layer 505. More specifically, the used amount of the first wash coat is twice as large as that of the second wash coat.

The particulate matter is mainly collected in the rear portion 240 of the filter 200, and particularly the ash and soot that originate from fuel or oil additives are accumulated there, and if the thickness of the second coating layer 505 is thicker, the back pressure is increased such that the accumulation efficiency is decreased.

However, in various embodiments of the present invention, the thickness of the second coating layer 505 is thinner than that of the first coating layer 500 such that the back pressure is relatively decreased, and the regeneration efficiency thereof is improved, even though the ash and soot is normally accumulated in the rear portion.

The front portion 230 and the rear portion 240 of the filter 200 are alternately dipped into the wash coat liquid so as to coat the inner surface of the channels 310 of the filter 200, and as the thickness of the wash coat becomes thicker, the diameters of the channels become relatively smaller.

In this case, the thickness of the second coating layer 505 can be thicker, but in various embodiments of the present invention, the thickness of the second coating layer 505 can be adjusted by reducing the first wash coat amount that is used for the second coating layer 505.

For convenience in explanation and accurate definition in the appended claims, the terms “front” and “rear” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. An exhaust gas filter system in which an asymmetrical channel, in which the diameter of an inlet being opened is larger than that of an outlet disposed and opened at a rear end surface, is formed, comprising: a first coating layer that is formed at an inner surface of a front portion of the channel by coating a first wash coat; and a second coating layer that is formed at an inner surface of a rear portion of the channel by coating a second wash coat; wherein inner cross section of the front portion is wider than inner cross section of the rear portion.
 2. The exhaust gas filter system of claim 1, wherein the thickness of the second coating layer is equal to or smaller than that of the first coating layer.
 3. The exhaust gas filter system of claim 1, wherein the first coating layer is formed in the front portion and the second coating layer is formed in the rear portion of the filter on the basis of a center line thereof.
 4. The exhaust gas filter system of claim 3, wherein the volume of the first wash coat that is used for the first coating layer is approximately twice as large as that of the second wash coat that is used for the second coating layer.
 5. The exhaust gas filter system of claim 4, wherein the weight of a noble metal that is contained in the first wash coat is equal to that of the noble metal that is contained in the second wash coat, and the concentration (weight/volume) of the noble metal is varied according to the weight of the noble metal.
 6. The exhaust gas filter system of claim 1, wherein a plurality of channels are formed in a flow direction of exhaust gas, the inlet of at least one among the channels is opened and the outlet thereof is closed, the inlet of at least another one among the channels is closed and the outlet thereof is opened, and the closed portions of the inlets are alternatively disposed and the closed portions of the outlets are alternatively disposed.
 7. The exhaust gas filter system of claim 1, wherein the front portion of the filter is soaked in a first wash coat liquid and the rear portion of the filter is soaked in a second wash coat liquid so as to respectively form the first coating layer and the second coating layer.
 8. The exhaust gas filter system of claim 7, wherein the thickness of the first coating layer is adjusted by controlling the used volume of the first wash coat.
 9. A passenger vehicle comprising an engine and the exhaust gas filter system of claim
 1. 